Hi all - cross posting this from the elixir-talk mailing list. I could use some help. I am currently evaluating Elixir and Phoenix for a performance-critical application for a Fortune 500 company. This could be another great case study for Elixir and Phoenix if I can show that it can meet our needs. Initial performance testing looked phenomenal, but I am running into some performance concerns that will force me to abandon this tech stack entirely if I cannot make the case.

The setup: an out-of-the box phoenix app using mix phoenix.new. No ecto. Returning a static json response. Basically a hello-world app.

The hardware:

• Macbook Pro, 16gb, 8 core, 2.5ghz, running elixir/phoenix natively, and also using docker container
• Amazon EC2 T2.Medium running Elixir Docker image

The tests: used ab, wrk, siege, artillery, curl with a variety of configurations. Up to 100 concurrent connections. Not super scientific, i know… but

No matter what I try, Phoenix logs out impressive numbers to stdout - generally on the order of 150-300 microseconds. However, none of the load testing tooling agrees. No matter the hardware or load test configuration, I see around 20-40 ms response times. The goal for the services that I am designing is 20ms and several thousand requests per second. The load tests that @chrismccord and others have published suggest that I should be able to expect 3ms or less when running localhost, but i’m not seeing anything close to that.

Would anyone be willing to work with me to look at some options here? I’d be incredibly grateful. Don’t make me go back to Java, please Is this even possible what I am asking?